Induction electric motor with flux injection in multiple reference frames

Abstract

A propulsion system for an electric vehicle includes an induction electric motor configured to generate torque for propulsion. The system includes a controller having a processor and tangible, non-transitory memory on which instructions are recorded for a method of suppressing tonal noises in a predefined motor speed range of the electric motor. The controller is adapted to simultaneously inject flux harmonics through respective injections in a rotor reference frame, a first flux reference frame and a second flux reference frame. The rotor reference frame is based in part on a rotor bar order and a rotor position. The first flux reference frame is based in part on a first induction order, the rotor position and a slip position. The second flux reference frame is based in part on a second induction order, the rotor position and the slip position.

What is claimed is: 
     
         1 . A propulsion system for an electric vehicle, comprising:
 an induction electric motor configured to generate torque for propulsion, the induction electric motor having a rotor and a stator;   a controller in communication with the induction electric motor and having a processor and tangible, non-transitory memory on which instructions are recorded for a method of suppressing tonal noises in a predefined motor speed range;   wherein the controller is adapted to simultaneously inject flux harmonics through a respective voltage injection in a plurality of reference frames, including a rotor reference frame, a first flux reference frame and a second flux reference frame;   wherein the rotor reference frame is based in part on a rotor bar order and a rotor position of the rotor;   wherein the first flux reference frame is based in part on a first induction order, the rotor position and a slip position; and   wherein the second flux reference frame is based in part on a second induction order, the rotor position and the slip position.   
     
     
         2 . The propulsion system of  claim 1 , wherein:
 the controller is configured to obtain a respective angular position of the rotor reference frame (θ 1 ) as θ 1 =(H 1 *θ r ), where H 1  is the rotor bar order and θ r  is the rotor position; and   the rotor bar order is defined as a ratio of a number of rotor bars in the rotor to the number of pole pairs.   
     
     
         3 . The propulsion system of  claim 2 , wherein the controller is configured to obtain the respective angular position of the first flux reference frame (θ 2 ) as θ 2 =H 2 *(θ r +θ s ), where H 2  is the first induction order, θ sl  is the slip position and θ r  is the rotor position. 
     
     
         4 . The propulsion system of  claim 3 , wherein the controller is configured to obtain the respective angular position of the second flux reference frame (θ 3 ) as: θ 3 =[(H 3 *θ r )−(2*θ sl )], where H 3  is the second induction order, θ s  is the slip position and θ r  is the rotor position. 
     
     
         5 . The propulsion system of  claim 4 , wherein the first induction order and the second induction order are based in part on a number of phases, stator slots and pole pairs in the induction electric motor. 
     
     
         6 . The propulsion system of  claim 4 , wherein the rotor bar order, the first induction order and the second induction order each have an identical value. 
     
     
         7 . The propulsion system of  claim 4 , wherein the rotor bar order, the first induction order and the second induction order each have different values. 
     
     
         8 . The propulsion system of  claim 4 , wherein the first induction order and the second induction order have an identical value and the rotor bar order has a different value. 
     
     
         9 . The propulsion system of  claim 4 , wherein the controller is configured to respectively vary a flux harmonics magnitude and a flux harmonics phase in the plurality of reference frames based on a commanded torque and a motor speed. 
     
     
         10 . A method of suppressing tonal noises in a propulsion system having an induction electric motor with a rotor and a stator, and a controller with a processor and tangible, non-transitory memory, the method comprising:
 generating torque for propulsion via the induction electric motor;   injecting flux harmonics through a respective voltage injection simultaneously in a plurality of reference frames, including a rotor reference frame, a first flux reference frame and a second flux reference frame;   selecting the rotor reference frame based in part on a rotor bar order and a rotor position of the rotor;   selecting the first flux reference frame based in part on a first induction order, the rotor position and a slip position; and   selecting the second flux reference frame based in part on a second induction order, the rotor position and the slip position.   
     
     
         11 . The method of  claim 10 , further comprising:
 obtaining a respective angular position of the rotor reference frame (θ 1 ) as θ 1 =(H 1 *θ r ), where H 1  is the rotor bar order and θ r  is the rotor position, the rotor bar order being defined as a ratio of a number of rotor bars in the rotor to the number of pole pairs, via the controller.   
     
     
         12 . The method of  claim 11 , further comprising:
 obtaining the respective angular position of the first flux reference frame (θ 2 ) as θ 2 =H 2 *(θ r +θ s ), where H 2  is the first induction order, θ sl  is the slip position and θ r  is the rotor position, via the controller.   
     
     
         13 . The method of  claim 12 , further comprising:
 obtaining the respective angular position of the second flux reference frame (θ 3 ) as: θ 3 =[(H 3 *θ r )−(2*θ sl )], where H 3  is the second induction order, θ sl  is the slip position and θ r  is the rotor position, via the controller.   
     
     
         14 . The method of  claim 13 , further comprising:
 selecting the first induction order and the second induction order based in part on a number of phases, stator slots and pole pairs in the induction electric motor.   
     
     
         15 . The method of  claim 13 , further comprising:
 selecting the rotor bar order, the first induction order and the second induction order to have an identical value.   
     
     
         16 . The method of  claim 13 , further comprising:
 selecting the rotor bar order, the first induction order and the second induction order to have different values.   
     
     
         17 . The method of  claim 13 , further comprising:
 varying respectively a flux harmonics magnitude and a flux harmonics phase in the plurality of reference frames based on a commanded torque and a motor speed, via the controller.   
     
     
         18 . An electric vehicle comprising:
 an induction electric motor configured to generate torque for propulsion, the electric motor having a rotor and a stator;   a controller in communication with the induction electric motor and having a processor and tangible, non-transitory memory on which instructions are recorded for a method of suppressing tonal noises;   wherein the controller is adapted to simultaneously inject flux harmonics through a respective voltage injection in a plurality of reference frames, including a rotor reference frame, a first flux reference frame and a second flux reference frame;   wherein the rotor reference frame is based in part on a rotor bar order and a rotor position of the rotor, the rotor bar order being defined as the ratio of a number of rotor bars in the rotor to the number of pole pairs;   wherein the controller is configured to obtain a respective angular position of the rotor reference frame (θ 1 ) as θ 1 =(H 1 *θ r ), where H 1  is the rotor bar order and θ r  is the rotor position;   wherein the first flux reference frame is based in part on a first induction order, the rotor position and a slip position; and   wherein the second flux reference frame is based in part on a second induction order, the rotor position and the slip position.   
     
     
         19 . The electric vehicle of  claim 18 , wherein the controller is configured to obtain the respective angular position of the first flux reference frame (θ 2 ) as θ 2 =H 2 +(θ r +θ s ), where H 2  is the first induction order, θ sl  is the slip position and θ r  is the rotor position. 
     
     
         20 . The electric vehicle of  claim 19 , wherein the controller is configured to obtain the respective angular position of the second flux reference frame (θ 3 ) as: θ 3 =[(H 3 +θ r )−(2+θ sl )], where H 3  is the second induction order, θ sl  is the slip position and θ r  is the rotor position.